Clinical studies related to cardiac pacing have shown that an optimal atrio-ventricular pacing delay (e.g., AV delay or PV delay) and/or an optimal interventricular pacing delay (e.g., VV delay) can improve cardiac performance. However, such optimal delays depend on a variety of factors that may vary over time. Thus, what is “optimal” may vary over time. An optimization of AV/PV pacing delay and/or VV pacing delay may be performed at implantation and sometimes, a re-optimization may be performed during a follow-up consultation. While such optimizations are beneficial, the benefits may not last due to changes in various factors related to device and/or cardiac function.
The following patents and patent applications set forth various systems and methods for allowing a pacemaker, implantable cardioverter-defibrillator (ICD) or other cardiac rhythm management (CRM) device to determine and/or adjust AV/PV/VV pacing delays so as to help maintain the pacing delays at optimal values: U.S. patent application Ser. No. 10/703,070, filed Nov. 5, 2003, entitled “Methods for Ventricular Pacing” now abandoned; U.S. patent application Ser. No. 10/974,123, filed Oct. 26, 2004 , now abandoned; U.S. patent application Ser. No. 10/986,273, filed Nov. 10, 2004, now U.S. Pat. No. 7,590,446 ; U.S. patent application Ser. No. 10/980,140, filed Nov. 1, 2004 , now abandoned; U.S. patent application Ser. No. 11/129,540, filed May 13, 2005 ; and U.S. patent application Ser. No. 11/952,743, filed Dec. 7, 2007 . See, also, U.S. patent application Ser. No. 12/328,605, filed Dec. 4, 2008, entitled “Systems and Methods for Controlling Ventricular Pacing in Patients with Long Intra-Atrial Conduction Delays” and U.S. patent application Ser. No. 12/132,563, filed Jun. 3, 2008, entitled “Systems and Methods for determining Intra-Atrial Conduction Delays using Multi-Pole Left Ventricular Pacing/Sensing Leads”. See, further, U.S. Pat. No. 7,248,925, to Bruhns et al., entitled “System and Method for Determining Optimal Atrioventricular Delay based on Intrinsic Conduction Delays.” At least some of the techniques are implemented within the QuickOpt™ systems of St. Jude Medical.
In particular, techniques were set forth within at least some of these patent documents for exploiting various inter-atrial and interventricular conduction delays to determine preferred or optimal AV/PV/VV pacing delays. Techniques were also set forth for exploiting the VV delays to determine which ventricles should be paced—the left ventricle (LV), the right ventricle (RV), both ventricles, or neither, and in which order. In at least some examples, the implanted device (or an external programming device in communication with the implanted device) performs a series of tests to determine intrinsic AV/PV and VV conduction delays from which preferred pacing delays are determined. In particular, an “A sense” test is performed to detect intrinsic intra-atrial delays from which preferred AV/PV pacing delays are determined. A “V sense” test is performed to detect intrinsic ventricular events from which an intrinsic interventricular conduction delay (Δ) is determined. An “RV pace” test and a separate “LV pace” test are performed to detect paced interventricular conduction delays (IVCD_RL and IVCD_LR, respectively) from which an intrinsic interventricular correction term (ε) is determined. The optimal VV delay for use in biventricular pacing is then set based on Δ and ε.
Issues can arise, though, when using a multi-pole LV lead for multi-site LV (MSLV) pacing. With a multi-pole LV lead—rather than having only a pair of tip and ring electrodes at a distal end of the lead—numerous electrodes are provided along the lead so that pacing/sensing can be performed at any of a variety of selected locations on or in the LV. With a multi-pole lead, the number of tests to be performed to optimize pacing delays can become numerous and time consuming. Typically, a separate V sense test would be employed for each of the LV electrodes (in combination with a particular RV electrode.) So, for example, for a quadra-pole LV lead, four V sense tests would be performed, one for each of the four electrodes of the LV lead. Likewise, typically, separate RV and LV pace tests would be employed for each of the LV electrodes (in combination with the RV electrode.) Again, for the example of a quadra-pole LV lead, four RV pace tests would be performed, one for each of the four electrodes of the LV lead. As such, the overall test time for optimizing VV pacing parameters for a multi-pole LV lead might be significant, with resulting costs and inconveniences to patient and clinician.
Accordingly, the invention is generally directed to providing improved test techniques for use with multi-pole leads to allow for more prompt and efficient determination of preferred or optimal VV pacing delays. Some aspects of the invention are directed to identifying the order by which a set of MSLV pacing pulses are to be delivered to various sites within the LV (i.e. to determine which LV site is to be paced first, which site is to be paced second, and so on.) Still other aspects are directed to addressing circumstances where the PV pacing delays to be used are longer than intrinsic PR delays or where the AV pacing delays to be used are longer than intrinsic AR delays.